CREATION_MODE on DOO_HEADERS_ALL is NULL for some orders

Summary:

We are seeing an inconsistency in the CREATION_MODE column for orders created via UI and API. In some cases, CREATION_MODE is null.

Content (please ensure you mask any confidential information):

We'd like to understand the purpose of CREATION_MODE in DOO_HEADERS_ALL. We need to determine whether the SO was created via API or UI. Can someone please explain why this field is sometimes NULL, and if it is unreliable, how can we determine whether the SO was created via API or UI? I did some more checking with a colleague, who has determined that copied SOs have a NULL CREATION_MODE.